1. Field of the Invention
The invention relates in general to storage and retrieval units, and more particularly, to a storage and retrieval unit having (a) a supporting carriage which is movable along a rack aisle on at least one substantially horizontal supporting rail by means of a drive; (b) a lifting platform carried along by the supporting carriage and intended for receiving storage items; (c) a lifting apparatus by means of which the lifting platform is movable in the vertical direction relative to the supporting carriage; (d) a stabilising device which prevents lateral deflection of the lifting platform relative to the supporting carriage.
2. Background Art
Storage and retrieval units of this type serve to store storage items in the compartments of high-bay racks and remove them from these again. The high-bay racks extend along a rack aisle in which the storage and retrieval unit is movable. To achieve a high turnover of the storage items and hence to minimise the overall size of the high-bay warehouse required for a given capacity, the speed with which the lifting platform can be moved from one position to the other should be as great as possible. Since the accelerated mass and the connecting device via which the lifting platform is connected to the supporting carriage form an oscillating system, a high acceleration usually also means the risk of large oscillations of the lifting platform.
Known storage and retrieval units of the type mentioned at the outset therefore have, besides the supporting carriage which is generally movable on the room floor, a massive column which is used to stabilise the lifting platform and on which the lifting platform is guided during its vertical movement. In order to achieve the necessary stiffness of the guide column, large masses are required. Storage and retrieval units of this type can reach a total weight of 25 metric tons. It is clear that enormous driving powers are required to be able to operate these storage and retrieval units with high accelerations. Despite the massive guide columns, considerable oscillation problems arise, especially as the natural frequencies of the oscillating system are relatively low on account of the high masses.
The object of the present invention is to design a storage and retrieval unit of the type mentioned at the outset in such a way that the lifting platform can be accelerated very rapidly and oscillation problems are minimised.